A flow rate sensor is configured to include: for example, an output mechanism that is configured to output an output signal such as a voltage corresponding to a flow rate of fluid flowing through a flow path; and a flow rate calculation part that is configured to calculate the flow rate on the basis of an output value indicated by the output signal and a flow rate characteristic function using the output value as an input variable.
The flow rate characteristic function has specific functional characteristics determined depending on the type or shape of a fluid resistance provided in the flow path, such as a laminar flow element, and for example, between a fluid resistance having a linear resistive flow path and a fluid resistance having a curved resistive flow path, the degree of the flow rate characteristic function, the tendency of a graph shape, and the like are significantly different.